PRECIOUS STONES 81
yellow
of off-color stones. The usual method is to paint the under side,
around the culet, with violet ink or an aniline dye. This is then
carefully rubbed down until the dye cannot be distinguished, but
leaving enough of the coloring matter to very much improve the apparent
color of the stone when faced up. The effect, of course, is only
temporary, and can easily be detected by cleaning the stone with
alcohol. Alany of these painted stones have undoubtedly been sold by
irregular dealers, who by this means induce the unwary to buy stones at
what appears to be much less than market value.
The cutting of diamonds is treated at length in another chapter devoted to that subject.
As
diamonds differ in hardness, so also do they vary in their power of
refraction and dispersion. In these qualities the Indian excel all
others, and the Brazilian come next, though the river stones of South
Africa resemble them very closely, and in some cases equal them.
In
this connection it may be of value to note that although any one can,
with the aid of a glass, discover the most minute flaws, and many have
an educated eye for color and have learned to appreciate the value of
good cutting, but few recognize the differences which exist among
diamonds in native " quality." This term is used by the writer to
designate that combination of qualities which give to some diamonds
an extraordinary fire and brilliancy. It arises from the superior
powers of reflection and dispersion possessed by some to an eminent
degree, and which, as has been stated, characterize the diamonds of
India, Brazil, and the river stones of the Cape. Not many realize that
there is a grading of " quality" quite distinct from, and independent
of, color and cut. Some off-color stones have a finer " quality" than
whiter goods, and some crystals cannot be cut to the brilliancy and
beauty of others which are similar, because they lack quality.
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